WebDAV Ordered Collections ProtocolUC Santa Cruz, Dept. of Computer Science1156 High StreetSanta CruzCA95064USejw@cse.ucsc.edugreenbytes GmbHSalzmannstrasse 152MuensterNW48159Germany+49 251 2807760+49 251 2807761julian.reschke@greenbytes.dehttp://greenbytes.de/tech/webdav/WEBDAV Working GroupWebDAVorderingordered collectionsprotocolORDERPATCHPosition header
This specification extends the WebDAV Distributed Authoring Protocol to
support server-side ordering of collection members. Of particular
interest are orderings that are not based on property values, and so
cannot be achieved using a search protocol's ordering option and cannot
be maintained automatically by the server. Protocol elements are
defined to let clients specify the position in the ordering of each
collection member, as well as the semantics governing the ordering.
Distribution of this document is unlimited. Please send comments to the
Distributed Authoring and Versioning (WebDAV) working group at
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Discussions of the WEBDAV working group are archived at URL:
http://lists.w3.org/Archives/Public/w3c-dist-auth/.
Since this document describes a set of extensions to the WebDAV Distributed
Authoring Protocol , itself an extension to the
HTTP/1.1 protocol, the augmented BNF used here to describe protocol elements
is exactly the same as described in Section 2.1 of HTTP .
Since this augmented BNF uses the basic production rules provided in Section
2.2 of HTTP, these rules apply to this document as well.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in .
This document uses XML DTD fragments as a purely notational convention. WebDAV
request and response bodies can not be validated due to the specific
extensibility rules defined in section 23 of and
due to the fact that all XML elements defined by this specification use the
XML namespace name "DAV:". In particular:
element names use the "DAV:" namespace,element ordering is irrelevant,extension elements (elements not already defined as valid child
elements) may be added anywhere, except when explicitly stated otherwise,extension attributes (attributes not already defined as valid for this
element) may be added anywhere, except when explicitly stated otherwise.
This specification builds on the collection infrastructure provided by
the WebDAV Distributed Authoring Protocol, adding support for the
server-side ordering of collection members.
There are many scenarios where it is useful to impose an ordering on a
collection at the server, such as expressing a recommended access order,
or a revision history order. The members of a collection might
represent the pages of a book, which need to be presented in order if
they are to make sense. Or an instructor might create a collection of
course readings, which she wants to be displayed in the order they are
to be read.
Orderings may be based on property values, but this is not always the
case. The resources in the collection may not have properties that can
be used to support the desired ordering. Orderings based on properties
can be obtained using a search protocol's ordering option, but orderings
not based on properties cannot. These orderings generally need to be
maintained by a human user.
The ordering protocol defined here focuses on support for such human-maintained
orderings. Its protocol elements allow clients to specify
the position of each collection member in the collection's ordering, as
well as the semantics governing the ordering. The protocol is designed
to allow support to be added in the future for orderings that are
maintained automatically by the server.
The remainder of this document is structured as follows:
defines terminology that will be used throughout the specification.
provides an overview of ordered collections.
describes how to create an ordered
collection, and discusses how to set a
member's position in the ordering of a collection.
explains how to change a collection
ordering. discusses listing the members of an
ordered collection. discusses the impact
on version-controlled collections (as defined in .
describes capability discovery.
through
discuss security, internationalization, and IANA considerations. The
remaining sections provide supporting information.
The terminology used here follows that in and
. Definitions of the terms resource, Uniform Resource
Identifier (URI), and Uniform Resource Locator (URL) are provided in
.
Ordered Collection
A collection for which the results from a PROPFIND request are
guaranteed to be in the order specified for that collection
Unordered Collection
A collection for which the client cannot depend on the
repeatability of the ordering of results from a PROPFIND request
Client-Maintained Ordering
An ordering of collection members that is maintained on the server
based on client requests specifying the position of each
collection member in the ordering
Server-Maintained Ordering
An ordering of collection members that is maintained automatically
by the server, based on a client's choice of ordering semantics
This document uses the terms "precondition", "postcondition" and "protected property" as defined in
. Servers MUST report pre-/postcondition failures
as described in section 1.6 of this document.
If a collection is unordered, the client cannot depend on the repeatability
of the ordering of results from a PROPFIND request. By specifying an
ordering for a collection, a client requires the server to follow that
ordering whenever it responds to a PROPFIND request on that collection.
Server-side orderings may be client-maintained or server-maintained.
For client-maintained orderings, a client must specify the ordering
position of each of the collection's members, either when the member is
added to the collection (using the Position header) or later (using the
ORDERPATCH method). For server-maintained orderings, the server
automatically positions each of the collection's members according to
the ordering semantics. This specification supports only client-maintained
orderings, but is designed to allow future extension to
server-maintained orderings.
A collection that supports ordering is not required to be ordered.
Concerns that it is not clear enough that DELETEing one internal
member MUST not affect the ordering of the remaining members.
Add clarification.
If a collection is ordered, each of its internal member URIs MUST be in
the ordering exactly once, and the ordering MUST NOT include any URI
that is not an internal member of the collection. The server is
responsible for enforcing these constraints on orderings. The server
MUST remove an internal member URI from the ordering when it is removed
from the collection.
Removing an internal member MUST NOT affect the ordering of the remaining
internal members.
The server MUST add an internal member URI to the
ordering when it is added to the collection.
Only one ordering can be attached to any collection. Multiple orderings
of the same resources can be achieved by creating multiple collections
referencing those resources, and attaching a different ordering to each
collection.
An ordering is considered to be part of the state of a collection
resource. Consequently, the ordering is the same no matter which URI is
used to access the collection and is protected by locks or access
control constraints on the collection.
A DAV:allprop PROPFIND request SHOULD NOT return any of the properties defined
in this document.
Indicates whether the collection is ordered and, if so, uniquely identifies
the semantics of the ordering being used. May also point to an explanation of
the semantics in human and / or machine-readable form. At a minimum, this
allows human users who add members to the collection to understand where to
position them in the ordering. This property cannot be set using PROPPATCH.
Its value can only be set by including the Ordering-Type header with a MKCOL
request or by submitting an ORDERPATCH request.
Ordering types are identified by URIs that uniquely identify the semantics
of the collection's ordering. The following two URIs are predefined:
The value DAV:custom indicates that the collection is ordered, but the
semantics governing the ordering are not being advertised.
The value DAV:unordered indicates that the collection is not ordered. That
is, the client cannot depend on the repeatability of the ordering of results
from a PROPFIND request.
An ordering-aware client interacting with an ordering-unaware server (e.g.,
one that is implemented only according to ) SHOULD
assume that if a collection does not have the DAV:ordering-type property, the
collection is unordered.
<!ELEMENT ordering-type (href) >
When a collection is created, the client MAY request that it be ordered
and specify the semantics of the ordering by using the new Ordering-Type
header (defined below) with a MKCOL request.
For collections that are ordered, the client SHOULD identify the semantics of
the ordering with a URI in the Ordering-Type header, although the client MAY
simply set the header value to DAV:custom to indicate that the collection is
ordered but the semantics of the ordering are not being advertised. Setting
the value to a URI that identifies the ordering semantics provides the
information a human user or software package needs to insert new collection
members into the ordering intelligently. Although the URI in the
Ordering-Type header MAY point to a resource that contains a definition of
the semantics of the ordering, clients SHOULD NOT access that resource, in
order to avoid overburdening its server. A value of DAV:unordered in the
Ordering-Type header indicates that the client wants the collection to be
unordered. If the Ordering-Type header is not present, the collection will
be unordered.
Additional Marshalling:
Ordering-Type = "Ordering-Type" ":" absoluteURI
; absoluteURI: see RFC2396, section 3
The URI "DAV:unordered" indicates that the collection is not ordered, while
"DAV:custom" indicates that the collection is to be ordered, but the
semantics of the ordering is not being advertised. Any other URI value
indicates that the collection is ordered, and identifies the semantics of the
ordering.
Additional Preconditions:
(DAV:ordered-collections-supported):
the server MUST support ordered collections
in the part of the URL namespace identified by the request URL.
Additional Postconditions:
(DAV:ordering-type-set):
if the Ordering-Type header was present, the request MUST have
created a new collection resource with the DAV:ordering-type being set
according to the Ordering-Type request header. The collection MUST be
ordered unless the ordering type was "DAV:unordered".
>> Request:
MKCOL /theNorth/ HTTP/1.1
Host: example.org
Ordering-Type: http://example.org/orderings/compass.html
>> Response:
HTTP/1.1 201 Created
In this example a new, ordered collection was created. Its DAV:ordering-type
property has as its value the URI from the Ordering-Type header,
http://example.org/orderings/compass.html. In this case, the URI identifies
the semantics governing a client-maintained ordering. As new members are
added to the collection, clients or end users can use the semantics to
determine where to position the new members in the ordering.
When a new member is added to a collection with a client-maintained ordering
(for example, with PUT, COPY, or MKCOL), its position in the ordering can be
set with the new Position header. The Position header allows the client to
specify that an internal member URI should be first in the collection's
ordering, last in the collection's ordering, immediately before some other
internal member URI in the collection's ordering, or immediately after some
other internal member URI in the collection's ordering.
Lisa Dusseault expressed concerns that clients that to "safe deletes"
(such as writing to a temp file, then moving to the original file)
will lose the original ordering. As the very same issue applies to
versioning (version histories lost) and ACLs, we aren't trying to
"fix" it here (it ain't broken). Clients should be encouraged to do
in-place editing using locks and etags.
No change.
Concerns that different server implementations may treat MOVE inside
the same collection as simple rename (not creating a new internal member),
or a sequence of LINK/UNLINK (in which case ordering will not be
preserved and the renamed resource would by default appear at the end
of the ordering (in absense of a Position header)).
I don't think making a special case for "move within a collection"
vs. "move outside of the collection" is worth optimizing, since it makes the
spec more complicated and is likely to be enough of a problem to some
servers to make it likely to not be followed anyway.
There doesn't appear to be consensus on this issue, hence we should leave it
out of the spec.
That said, given that we had discussion on this issue, it makes sense to try
and capture some of that discussion in the specification, so that
implementors aren't operating in a total vacuum on this issue. Minimally,
the spec. should note that this behavior is intentionally undefined.
Add clarification.
If the Position request header is not used when adding a member to an
ordered collection, then:
If the request is replacing an existing resource, the server MUST
preserve the present ordering.
If the request is adding a new internal member URI to the collection,
the server MUST append the new member to the end of the ordering.
Note to implementors: this specification does not mandate a specific implementation of
MOVE operations within the same parent collection. Therefore, servers
may either implement this as a simple rename operation (preserving the
collection member's position), or as a sequence of "remove" and "add"
(causing the semantics of "adding a new member" to apply). Future
revisions of this specification may specify this behaviour more precisely
based on future implementation experience.
Additional Marshalling:
Position = "Position" ":" ("first" | "last" |
(("before" | "after") segment))
segment is defined in Section 3.3 of .
The segment is interpreted relative to the collection to which the new
member is being added.
When the Position header is present, the
server MUST insert the new member into the ordering at the
specified location.
The "first" keyword indicates the new member is put in the beginning
position in the collection's ordering, while "last" indicates the new
member is put in the final position in the collection's ordering. The
"before" keyword indicates the new member is added to the collection's
ordering immediately prior to the position of the member identified in
the segment. Likewise, the "after" keyword indicates the new member is
added to the collection's ordering immediately following the position of
the member identified in the segment.
If the request is replacing an existing resource, and the Position
header is present, the server MUST remove the internal member URI from
its previous position, and then insert it at the requested position.
Additional Preconditions:
(DAV:collection-must-be-ordered): the target collection MUST be ordered.
(DAV:segment-must-identify-member): the referenced segment MUST identify a resource that
exists and is different from the affected resource.
Additional Postconditions:
(DAV:position-set):
if a Position header was present, the
request MUST have created the new collection member at the specified
position.
>> Request:
COPY /~user/dav/spec08.html HTTP/1.1
Host: example.org
Destination: http://example.org/~slein/dav/spec08.html
Position: after requirements.html
>> Response:
HTTP/1.1 201 Created
This request resulted in the creation of a new resource at
example.org/~slein/dav/spec08.html. The Position header in this
example caused the server to set its position in the ordering of the
/~slein/dav/ collection immediately after requirements.html.
>> Request:
MOVE /i-d/draft-webdav-prot-08.txt HTTP/1.1
Host: example.org
Destination: http://example.org/~user/dav/draft-webdav-prot-08.txt
Position: first
>> Response:
HTTP/1.1 409 Conflict
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:error xmlns:D="DAV:">
<D:collection-must-be-ordered/>
</D:error>
In this case, the server returned a 409 (Conflict) status code because
the /~user/dav/ collection is an unordered collection.
Consequently, the server was unable to satisfy the Position header.
The ORDERPATCH method is used to change the ordering semantics of a
collection or to change the order of the collection's members in the
ordering or both.
The server MUST apply the changes in the order they appear in the order
XML element. The server MUST either apply all the changes or apply none
of them. If any error occurs during processing, all executed changes
MUST be undone and a proper error result returned.
If an ORDERPATCH request changes the ordering semantics, but does not
completely specify the order of the collection members, the server MUST
assign a position in the ordering to each collection member for which a
position was not specified. These server-assigned positions MUST all
follow the last one specified by the client. The result is that all
members for which the client specified a position are at the beginning
of the ordering, followed by any members for which the server assigned
positions.
If an ORDERPATCH request does not change the ordering semantics, any
member positions not specified in the request MUST remain unchanged.
A request to reposition a collection member at the same place in the
ordering is not an error.
If an ORDERPATCH request fails, the server state preceding the request MUST be restored.
Additional Marshalling:
The request body MUST be DAV:orderpatch element.
<!ELEMENT orderpatch (ordering-type?, order-member*) >
<!ELEMENT order-member (segment, position) >
<!ELEMENT position (first | last | before | after)>
<!ELEMENT segment (#PCDATA)>
<!ELEMENT first EMPTY >
<!ELEMENT last EMPTY >
<!ELEMENT before segment >
<!ELEMENT after segment >
PCDATA value: segment, as defined in section 3.3 of .
The DAV:ordering-type property is modified according to the DAV:ordering-type
element.
The ordering of internal member URIs in the collection identified by the
Request-URI is changed based on instructions in the
order-member
XML elements in the order they appear in the request. The
order-member XML
elements identify the internal member URIs whose positions are to be
changed, and describe their new positions in the ordering.
Each new position can be specified as first in the ordering, last in the
ordering, immediately before some other internal member URI, or
immediately after some other internal member URI.
If a response body for a successful request is included, it MUST
be a DAV:orderpatch-response XML element. Note that this
document does not define any elements for the ORDERPATCH
response body, but the DAV:orderpatch-response element is
defined to ensure interoperability between future extensions that
do define elements for the ORDERPATCH response body.
<!ELEMENT orderpatch-response ANY>
Since multiple changes can be requested in a single ORDERPATCH request,
if any problems are encountered, the server MUST return a 207 (Multi-Status)
response (defined in ), containing DAV:response
elements for either the request-URI (when the DAV:ordering-type could not
be modified) or URIs of collection members to be repositioned (when an
individual positioning request expressed as DAV:order-member could not be
fulfilled).
Preconditions:
(DAV:collection-must-be-ordered): see .(DAV:segment-must-identify-member): see .
Postconditions:
(DAV:ordering-type-set):
if the request body contained a DAV:ordering-type element, the
request MUST have set the DAV:ordering-type property of the collection
to the value specified in the request.
(DAV:ordering-modified):
if the request body contained DAV:order-member elements, the request
MUST have set the ordering of internal member URIs in the collection
identified by the request-URI based on the instructions in the
DAV:order-member elements.
Consider a collection /coll-1/ whose DAV:ordering-type is DAV:whim, with
bindings ordered as follows:
three.html
four.html
one.html
two.html
>> Request:
ORDERPATCH /coll-1/ HTTP/1.1
Host: example.org
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
<?xml version="1.0" ?>
<d:orderpatch xmlns:d="DAV:">
<d:ordering-type>
<d:href>http://example.org/inorder.ord</d:href>
</d:ordering-type>
<d:order-member>
<d:segment>two.html</d:segment>
<d:position><d:first/></d:position>
</d:order-member>
<d:order-member>
<d:segment>one.html</d:segment>
<d:position><d:first/></d:position>
</d:order-member>
<d:order-member>
<d:segment>three.html</d:segment>
<d:position><d:last/></d:position>
</d:order-member>
<d:order-member>
<d:segment>four.html</d:segment>
<d:position><d:last/></d:position>
</d:order-member>
</d:orderpatch>
>> Response:
HTTP/1.1 200 OK
In this example, after the request has been processed, the collection's
ordering semantics are identified by the URI http://example.org/inorder.ord.
The value of the collection's DAV:ordering-type property has been set to this
URI. The request also contains instructions for changing the positions of the
collection's internal member URIs in the ordering to comply with the new
ordering semantics. As the
DAV:order-member elements are required to be processed in
the order they appear in the request, two.html is moved
to the beginning of the ordering, and then one.html is moved to the
beginning of the ordering. Then three.html is moved to the end of the
ordering, and finally four.html is moved to the end of the ordering.
After the request has been processed, the collection's ordering is as
follows:
one.html
two.html
three.html
four.html
Consider a collection /coll-1/ with members ordered as follows:
nunavut.map
nunavut.img
baffin.map
baffin.desc
baffin.img
iqaluit.map
nunavut.desc
iqaluit.img
iqaluit.desc
>> Request:
ORDERPATCH /coll-1/ HTTP/1.1
Host: www.nunanet.com
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
<?xml version="1.0" ?>
<d:orderpatch xmlns:d="DAV:">
<d:order-member>
<d:segment>nunavut.desc</d:segment>
<d:position>
<d:after>
<d:segment>nunavut.map</d:segment>
</d:after>
</d:position>
</d:order-member>
<d:order-member>
<d:segment>iqaluit.map</d:segment>
<d:position>
<d:after>
<d:segment>pangnirtung.img</d:segment>
</d:after>
</d:position>
</d:order-member>
</d:orderpatch>
>> Response:
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
<?xml version="1.0" ?>
<d:multistatus xmlns:d="DAV:">
<d:response>
<d:href>http://www.nunanet.com/coll-1/iqaluit.map</d:href>
<d:status>HTTP/1.1 403 Forbidden</d:status>
<d:responsedescription>
<d:error><d:segment-must-identify-member/></d:error>
pangnirtung.img is not a collection member.
</d:responsedescription>
</d:response>
</d:multistatus>
In this example, the client attempted to position iqaluit.map after a
URI that is not an internal member of the collection /coll-1/.
The server responded to this client error with a 403 (Forbidden) status code,
indicating the failed precondition DAV:segment-must-identify-member. Because
ORDERPATCH is an atomic method, the request to reposition
nunavut.desc (which would otherwise have succeeded) failed as well, but doesn't
need to be expressed in the multistatus response body.
A PROPFIND request is used to retrieve a listing of the members of an
ordered collection, just as it is used to retrieve a listing of the
members of an unordered collection.
However, when responding to a PROPFIND on an ordered collection, the
server MUST order the response elements according to the ordering
defined on the collection. If a collection is unordered, the client
cannot depend on the repeatability of the ordering of results from a
PROPFIND request.
In a response to a PROPFIND with Depth: infinity, members of different
collections may be interleaved. That is, the server is not required to
do a breadth-first traversal. The only requirement is that the members
of any ordered collection appear in the order defined for the
collection. Thus for the hierarchy illustrated in the following figure,
where collection A is an ordered collection with the ordering B C D,
A
/|\
/ | \
B C D
/ /|\
E F G H
it would be acceptable for the server to return response elements in the
order A B E C F G H D. In this response, B, C, and D appear in the
correct order, separated by members of other collections. Clients can
use a series of Depth: 1 PROPFIND requests to avoid the complexity of
processing Depth: infinity responses based on depth-first traversals.
Suppose a PROPFIND request is submitted to /MyColl/, which has its
members ordered as follows.
/MyColl/
lakehazen.html
siorapaluk.html
iqaluit.html
newyork.html
>> Request:
PROPFIND /MyColl/ HTTP/1.1
Host: example.org
Depth: 1
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" ?>
<D:propfind xmlns:D="DAV:">
<D:prop xmlns:J="http://example.org/jsprops/">
<D:ordering-type/>
<D:resourcetype/>
<J:latitude/>
</D:prop>
</D:propfind>
>> Response:
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" ?>
<D:multistatus xmlns:D="DAV:"
xmlns:J="http://example.org/jsprops/">
<D:response>
<D:href>http://example.org/MyColl/</D:href>
<D:propstat>
<D:prop>
<D:ordering-type>
<D:href>DAV:custom</D:href>
</D:ordering-type>
<D:resourcetype><D:collection/></D:resourcetype>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<J:latitude/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>http://example.org/MyColl/lakehazen.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype/>
<J:latitude>82N</J:latitude>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<D:ordering-type/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href
>http://example.org/MyColl/siorapaluk.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype/>
<J:latitude>78N</J:latitude>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<D:ordering-type/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>http://example.org/MyColl/iqaluit.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype/>
<J:latitude>62N</J:latitude>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<D:ordering-type/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>http://example.org/MyColl/newyork.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype/>
<J:latitude>45N</J:latitude>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
<D:propstat>
<D:prop>
<D:ordering-type/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:propstat>
</D:response>
</D:multistatus>
In this example, the server responded with a list of the collection
members in the order defined for the collection.
The Versioning Extensions to WebDAV introduce the
concept of versioned collections, recording both the dead properties and
the set of internal version-controlled bindings. This section defines how
this feature interacts with ordered collections.
This specification considers both the ordering type (DAV:ordering-type property)
and the ordering of collection members to be part of the state of a collection.
Therefore both MUST be recorded upon CHECKIN or VERSION-CONTROL, and both MUST be
restored upon CHECKOUT, UNCHECKOUT or UPDATE (where for compatibility with
RFC3253, only the ordering of version-controlled members needs to be maintained).
For ordered collections, the DAV:version-controlled-binding elements MUST appear
in the ordering defined for the checked-in ordered collection.
The DAV:ordering-type property records the DAV:ordering-type property of
the checked-in ordered collection.
Additional Postconditions:
(DAV:initialize-version-controlled-bindings-ordered): If the request-URL
identified a both ordered and version-controlled collection, then the child
elements of DAV:version-controlled-binding-set of the new collection version
MUST appear in the ordering defined for that collection.
(DAV:initialize-collection-version-ordering-type): If the request-URL
identified a both ordered and version-controlled collection, then the
DAV:ordering-type property of the new collection version MUST be a copy
of the collection's DAV:ordering-type property.
Additional Postconditions:
(DAV:initialize-version-history-bindings-ordered): If the request has been
applied to a collection version with a DAV:ordering-type other than "DAV:unordered",
the bindings in the new working collection MUST be ordered according to the collection version's
DAV:version-controlled-binding-set property.
(DAV:initialize-ordering-type): If the request has been
applied to a collection version, the DAV:ordering-type property of
the new working collection MUST be initialized from the collection
version's DAV:ordering-type property.
Clarify effect of UPDATE of a versioned collection on ordering of
non version-controlled members.
Ordering is server-defined.
Additional Postconditions:
(DAV:update-version-controlled-collection-members-ordered): If the request
modified the DAV:checked-in version of a version-controlled collection
and the DAV:ordering-type for the checked-in version is not unordered ("DAV:unordered"),
the version-controlled members MUST be ordered according to the checked-in
version's DAV:version-controlled-binding-set property.
The ordering of non-version-controlled members is server-defined."
(DAV:update-version-ordering-type): If the request modified the
DAV:checked-in version of a version-controlled collection, the
DAV:ordering-type property MUST be updated from the checked-in version's
property.
Sections 9.1 and 15 of describe the use of compliance classes
with the DAV header in responses to OPTIONS, to indicate which parts of
the Web Distributed Authoring protocols the resource supports. This
specification defines an OPTIONAL extension to . It defines a
new compliance class, called ordered-collections, for use with the DAV header in
responses to OPTIONS requests. If a collection resource does support
ordering, its response to an OPTIONS request may indicate that it does,
by listing the new ORDERPATCH method as one it supports, and by listing
the new ordered-collections compliance class in the DAV header.
When responding to an OPTIONS request, only a collection or a null
resource can include ordered-collections in the value of the DAV header. By
including ordered-collections, the resource indicates that its internal member
URIs can be ordered. It implies nothing about whether any collections
identified by its internal member URIs can be ordered.
Furthermore, RFC 3253 introduces the live properties
DAV:supported-method-set (section 3.1.3) and DAV:supported-live-property-set
(section 3.1.4). Servers MUST support these properties as defined in RFC 3253.
>> Request:
OPTIONS /somecollection/ HTTP/1.1
Host: example.org
>> Response:
HTTP/1.1 200 OK
Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE
Allow: MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, ORDERPATCH
DAV: 1, 2, ordered-collections
The DAV header in the response indicates that the resource
/somecollection/ is level 1 and level 2 compliant, as defined in
. In addition, /somecollection/ supports ordering. The Allow
header indicates that ORDERPATCH requests can be submitted to
/somecollection/.
>> Request:PROPFIND /somecollection HTTP/1.1
Depth: 0
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
<?xml version="1.0" encoding="UTF-8" ?>
<propfind xmlns="DAV:">
<prop>
<supported-live-property-set/>
<supported-method-set/>
</prop>
</propfind>
>> Response:HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
<?xml version="1.0" encoding="utf-8" ?>
<multistatus xmlns="DAV:">
<response>
<href>http://example.org/somecollection</href>
<propstat>
<prop>
<supported-live-property-set>
<supported-live-property>
<prop><ordering-type/></prop>
</supported-live-property>
<!-- ... other live properties omitted for brevity ... -->
</supported-live-property-set>
<supported-method-set>
<supported-method name="COPY" />
<supported-method name="DELETE" />
<supported-method name="GET" />
<supported-method name="HEAD" />
<supported-method name="LOCK" />
<supported-method name="MKCOL" />
<supported-method name="MOVE" />
<supported-method name="OPTIONS" />
<supported-method name="ORDERPATCH" />
<supported-method name="POST" />
<supported-method name="PROPFIND" />
<supported-method name="PROPPATCH" />
<supported-method name="PUT" />
<supported-method name="TRACE" />
<supported-method name="UNLOCK" />
</supported-method-set>
</prop>
<status>HTTP/1.1 200 OK</status>
</propstat>
</response>
</multistatus>
Note that actual responses MUST contain a complete list of supported live
properties.
This section is provided to make WebDAV applications aware of the
security implications of this protocol.
All of the security considerations of HTTP/1.1 and the WebDAV
Distributed Authoring Protocol specification also apply to this protocol
specification. In addition, ordered collections introduce a new
security concern. This issue is detailed here.
There may be some risk of denial of service at sites that are advertised
in the DAV:ordering-type property of collections. However, it is
anticipated that widely-deployed applications will use hard-coded values
for frequently-used ordering semantics rather than looking up the
semantics at the location specified by DAV:ordering-type. This risk will
be further reduced if clients observe the recommendation of
that they not send requests to the URI in DAV:ordering-type.
This specification follows the practices of in encoding all
human-readable content using and in the treatment of names.
Consequently, this specification complies with the IETF Character Set
Policy .
WebDAV applications MUST support the character set tagging, character
set encoding, and the language tagging functionality of the XML
specification. This constraint ensures that the human-readable content
of this specification complies with .
As in , names in this specification fall into three categories:
names of protocol elements such as methods and headers, names of XML
elements, and names of properties. Naming of protocol elements follows
the precedent of HTTP, using English names encoded in USASCII for
methods and headers. The names of XML elements used in this
specification are English names encoded in UTF-8.
For error reporting, follows the convention of HTTP/1.1 status
codes, including with each status code a short, English description of
the code (e.g., 423 Locked). Internationalized applications will ignore
this message, and display an appropriate message in the user's language
and character set.
This specification introduces no new strings that are displayed to users
as part of normal, error-free operation of the protocol.
For rationales for these decisions and advice for application
implementors, see .
This document uses the namespaces defined by for properties and
XML elements. All other IANA considerations mentioned in also
apply to this document.
To be supplied by the RFC Editor.
To be supplied by the RFC Editor.
This document has benefited from significant contributions from
Geoff Clemm, Jason Crawford, Jim Davis, Chuck Fay and Judith Slein.
This draftdocument has benefited from thoughtful discussion by Jim Amsden, Steve
Carter, Tyson Chihaya, Geoff Clemm, Ken Coar, Ellis Cohen, Bruce Cragun,
Jim Davis, Spencer Dawkins, Mark Day, Rajiv Dulepet, David Durand,
Lisa Dusseault, Chuck Fay, Roy Fielding, Yaron Goland, Fred
Hitt, Alex Hopmann, Marcus Jager, Chris Kaler, Manoj Kasichainula, Rohit
Khare, Daniel LaLiberte, Steve Martin, Larry
Masinter, Jeff McAffer, Surendra Koduru Reddy, Max Rible, Sam Ruby, Bradley
Sergeant, Nick Shelness, John Stracke, John Tigue, John Turner, Kevin Wiggen,
and others.
IETF Policy on Character Sets and LanguagesUNINETTP.O.Box 6883 ElgeseterN-7002 TRONDHEIMNORWAY+47 73 59 70 94Harald.T.Alvestrand@uninett.noApplications
Internet Engineering Task Forcecharacter encodingUniform Resource Identifiers (URI): Generic SyntaxWorld Wide Web ConsortiumMIT Laboratory for Computer Science, NE43-356545 Technology SquareCambridgeMA02139+1(617)258-8682timbl@w3.orgDepartment of Information and Computer ScienceUniversity of California, IrvineIrvineCA92697-3425+1(949)824-1715fielding@ics.uci.eduXerox PARC3333 Coyote Hill RoadPalo AltoCA94034+1(415)812-4333masinter@parc.xerox.comApplications
uniform resourceURI
A Uniform Resource Identifier (URI) is a compact string of characters
for identifying an abstract or physical resource. This document
defines the generic syntax of URI, including both absolute and
relative forms, and guidelines for their use; it revises and replaces
the generic definitions in RFC 1738 and RFC 1808.
This document defines a grammar that is a superset of all valid URI,
such that an implementation can parse the common components of a URI
reference without knowing the scheme-specific requirements of every
possible identifier type. This document does not define a generative
grammar for URI; that task will be performed by the individual
specifications of each URI scheme.
This paper describes a "superset" of operations that can be applied
to URI. It consists of both a grammar and a description of basic
functionality for URI. To understand what is a valid URI, both the
grammar and the associated description have to be studied. Some of
the functionality described is not applicable to all URI schemes, and
some operations are only possible when certain media types are
retrieved using the URI, regardless of the scheme used.
Key words for use in RFCs to Indicate Requirement LevelsHarvard University1350 Mass. Ave.CambridgeMA 02138- +1 617 495 3864-General
keyword
In many standards track documents several words are used to signify
the requirements in the specification. These words are often
capitalized. This document defines these words as they should be
interpreted in IETF documents. Authors who follow these guidelines
should incorporate this phrase near the beginning of their document:
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
RFC 2119.
Note that the force of these words is modified by the requirement
level of the document in which they are used.
Extensible Markup Language (XML) 1.0 (2nd ed)Textuality and Netscapetbray@textuality.comMicrosoftjeanpa@microsoft.comUniversity of Illinois at Chicago and Text Encoding Initiativecmsmcq@uic.eduSun Microsystemseve.maler@east.sun.comHypertext Transfer Protocol -- HTTP/1.1University of California, Irvinefielding@ics.uci.eduW3Cjg@w3.orgCompaq Computer Corporationmogul@wrl.dec.comMIT Laboratory for Computer Sciencefrystyk@w3.orgXerox Corporationmasinter@parc.xerox.comMicrosoft Corporationpaulle@microsoft.comW3Ctimbl@w3.orgHTTP Extensions for Distributed Authoring -- WEBDAVMicrosoft Corporationyarong@microsoft.comDept. Of Information and Computer Science, University of California, Irvineejw@ics.uci.eduNetscapeasad@netscape.comNovellsrcarter@novell.comNovelldcjensen@novell.comVersioning Extensions to WebDAVRational Softwaregeoffrey.clemm@rational.comIBMjamsden@us.ibm.comIBMtim_ellison@uk.ibm.comMicrosoftckaler@microsoft.comUC Santa Cruz, Dept. of Computer Scienceejw@cse.ucsc.edu
<!ELEMENT orderpatch (ordering-type?, order-member*) >
<!ELEMENT order-member (segment, position) >
<!ELEMENT ordering-type (href) >
<!ELEMENT position (first | last | before | after)>
<!ELEMENT first EMPTY >
<!ELEMENT last EMPTY >
<!ELEMENT before segment >
<!ELEMENT after segment >
<!ELEMENT segment (#PCDATA)>
Updated contact information for all previous authors.
Specify charset when using text/xml media type.
Made sure artwork fits into 72 columns.
Removed "Public" header from OPTIONS example.
Added Julian Reschke to list of authors.
Fixed broken XML in PROPFIND example and added DAV:orderingtype to list
of requested properties.
Added support for DAV:supported-live-property-set and DAV:supported-method-set
as mandatory features.
Updated change log to refer to expired draft version as "December 1999" version.
Started rewrite marshalling in RFC3253-style and added precondition and postcondition
definitions.
On his request, removed Geoff Clemm's name from the author list (moved to
Acknowledgments).
Renamed "References" to "Normative References".
Removed reference to "MKREF" method.
Added a set of issues regarding marshalling.
Changed host names to use proper "example" domain names (no change tracking).
Fixed host/destination header conflicts. Fixed "allow" header (multiline).
Removed irrelevant response headers. Abbreviated some URIs (no change tracking).
Removed Jim Davis and Chuck Fay from the author list (and added them to the Acknowledgements section).
Updated section on setting the position when adding new members, removed old section on Position header.
Started work on Index section.
Changed structure for section 7 (no change tracking).
Removed header and XML elements section (contents moved to other sections).
Started new section on relation to versioned collections as per RFC3253.
Do not return 424's for in ORDERPATCH multistatus (it's atomic anyway).
Added proper reference to definition of "Coded-URL".
Closed issue ordering-type-values (content model simplified and XML element / DAV
property renamed) and updated examples.
Renamed precondition DAV:orderingtype-set to DAV:ordering-type-set (no change tracking).
Closed issue ordered-header-name (header name changed to "ordering-type",
contents matches live property).
Closed issue ordermember-format (now takes segment instead of href).
Renamed compliance class to "ordered-collections" for consistency with newer
specs, and to allow detection of compliance to final version of spec.
Updated reference to XML spec to 1.0, 2nd edition.
Typos fixed.
Renamed DAV:ordermember to DAV:order-member.
Made RFC3253-compatible pre/postcondition handling a MUST requirement.
Reference definition of "protected property" from RFC3253.
Added explanation of role of DTD fragments to Notation section.
Clarified semantics for operations on versioned collections and collection versions.
Added atomicity statement for ORDERPATCH method.
Added issues "4.1-DELETE-behaviour", "6.1-safe-update", "6.1-when-are-members-added"
and "9.4-UPDATE-non-version-controlled-members" and resolved them.
Added new "contributors" section, and mention original authors such as Judith Slein there.